The number of VMs to be provisioned beforehand.
This allows to speed up CI runs by starting them immediately without waiting for a VM to get booted.

If the number is set to 0:

No VMs provisioned in advance.

If the number is bigger than 0:

The plugin provisions new VMs to meet the value.

If instances Min is bigger than instance Cap:

The plugin provisions max number of VMs specified in instance Cap (the smallest of cloud and template options).

The plugin checks the number of running VMs once in 2 minutes.

Pre-provisoned VMs will be deleted based on the retention policy.